Some aspects of gas transfer in the Warburg respirometer

[摘要] A mathematical model for the Warburg constant volume respirometer was developed to describe the effect of oxygen mass transfer on kinetics of bacterial growth or oxygen uptake. Oxygen mass transfer coefficients and oxygen limited reaction rate constants were determined for thesystem using air, 21%, 50%, and 100% oxygen gas phases.The equations developed areNon-Limited Oxygen UptakeOxygen Limited Oxygen UptakeSubstrate Limited Oxygen Uptakeoccurred in the range 60-110 mg/1 oxygen uptake for air systems. The mass transfer coefficient K1a was 0.264 liters/hr for fifty milliliter samples, 72 min-1 shake rate at 20°C. The oxygen limited reaction rate constant can be calculated from the equationk' = 0.0105/P - 0.00363 [33] Constants for equationcould not be evaluated from the data obtained.Equation [15a] predicts oxygen uptake values within+/- 5% of the experimental values for 1.0 atmospheres oxygen partial pressure +/- 8% for 0.50 atmospheres oxygen partial pressure, +/- 25% for 0.21 atmospheres oxygen partial pressure, and +/- 30% for air systems. Equation [15a] is applicable from the point of deviation from exponential growthto the point of substrate limitation. Substrate limitation occurs at 36.2% of the theoretical oxygen demand for glutamic acid systems and at 29.8% of the theoretical oxygen demand for glucose systems.Application of all equations requires knowledge of the equation constants for the particular seed and substrate used. Of the constants the exponential growth rate constant and the point of deviation from exponential growth are undefined and vary widely with seed material. Equating equations [5] and [15a] give the initial point for equation [15a].Equations to describe carbon dioxide partial pressurewithin the Warburg: system were developed. Calculated car-bon dioxide partial pressures indicate that carbon dioxide is not limiting in the Warburg system. The equations were not subject to verification in the study reported.

[发布机构] Rice University